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Contact an Enterprise SpecialistTrueNAS CORE Nightly Development Documentation
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SLOG Overprovisioning
2 minute read.
Over-provisioning SLOG SSDs is useful for different scenarios. The most useful benefit of over-provisioning is greatly extending SSD life. Over-provisioning an SSD distributes the total number of writes and erases across more flash blocks on the drive.
Seagate provides a thoughtful investigation into over-provisioning SSDs here: https://www.seagate.com/blog/ssd-over-provisioning-benefits-master-ti/.
Some SATA devices are limited to one resize per power cycle. Some BIOS can block resize during boot and require a live power cycle.
To over provision a SLOG device, log in to TrueNAS and go to System > Advanced.
Enter an over-provision value corresponding to the new size in GB in the Log (Write Cache) Overprovision Size in GiB field. When this value is applied, the over-provision value is applied whenever a pool is created with a SLOG device.
It is impossible to restore an over-provisioned SLOG device back to original capacity without running the Erasing the over-provision setting in System > Advanced Log (Write Cache) Overprovision Size in GiB field and setting to none prevents future SLOG devices from being over-provisioned.Web Interface
disk_resize command after first destroying the pool it was part of and issuing a full power cycle.Only one over-provision/under-provision operation occurs per power cycle.